Another thing is the Man United midfield. Defending starts from the midfield. A poor midfield will make the defense suffer when a defense is suffering, they'll surely concede goals.
I've been saying these things forever. United needs to work on their squad. They don't have a squad that can fight for the league or the Champions League. They will not even make the top 4 in the league.
The midfielder's are meant to shield the defenders since they're currently under crises. Mason Mount should be used on the flanks and not behind Bruno Fernandez, Erik Ten Hag will not drop Bruno Fernandez deep bit Mason Mount looks odd in that position.
They also need a midfielder that holds the ball amd keeps possession very well. Mainoo Kobbie the young player would have been the best player to execute this plan for Erik Ten Hag, he should be paired with Casemiro.
Not making the top four depends on Erik Ten Hag amd that would be a fatal flaw. If he is wise, he should have learned the hard way from coaches of the past that failed.
Erik Ten Hag might be right, but, I'm still not comfortable with him fighting Jadon Sancho off the squad. He should do better.